1. Field of the Invention
The present invention relates to a turbomachine having a rotor shaft, which is mounted in a bearing arrangement containing a hydrodynamic axial bearing, and having a rotor disposed on the rotor shaft. The term “hydrodynamic axial bearing” refers to commercially available axial slide bearings that are frequently used in turbomachine construction.
2. The Prior Art
In known turbomachines known having the characteristics described initially, the hydrodynamic axial bearing serves two purposes. The hydrodynamic axial bearing serves both to absorb the axial forces that occur when the rotor shaft is not moving, and to absorb the axial thrusts that occur during operation of the turbomachine. The axial thrusts depend on the pressure conditions at the rotor, the type of rotor, as well as on the shaft seal geometry. In the case of turbomachines configured as compressors, in particular, the high pre-pressure of the fluid to be compressed results in high axial thrusts when the machine is at rest, and thereby also when the machine is started up. In the design of the hydrodynamic axial bearing, there is therefore the problem that the hydrodynamic axial bearing must absorb the axial forces that occur during the stopped state and during start-up of the turbomachine, and the axial forces that occur during operation at the rated speed of rotation. A design of the hydrodynamic axial bearing coordinated only with operation at the rated speed of rotation is therefore not possible, so that corresponding disadvantages with regard to the dissipated energy of the bearing as well as its dimensioning have to be accepted.